1. Field of the Invention
The present invention relates to a three-dimensional model generating method, a three-dimensional model generating system, and a three-dimensional model generating program generating a three-dimensional model in a CAD system using measurement data obtained by measuring a measured object with a coordinate measuring device.
2. Description of Related Art
Conventionally, as an example of a reverse engineering method or a simple product design method, a technology is known in which a three-dimensional model is automatically generated in a CAD system using measurement data obtained by measuring a measured object with a coordinate measuring device. Technology disclosed by Japanese Patent Laid-open Publication No. 2003-345839, for example, is configured such that data for plane elements representing surfaces of a measured object is created using measurement data (point group data) obtained by measuring the measured object, the plane elements are connected and compound plane element data representing linking surfaces is created, and a three-dimensional solid model is generated using a space enclosed by the compound plane element data.
However, in the above-described conventional three-dimensional model generating method, due to a measurement error when measuring the measured object with the coordinate measuring apparatus or a conversion error in converting from measurement data to plane element data, a situation may arise in which positions connecting the plane element data are offset and unable to form a connection, making it difficult to generate a three-dimensional model having a desired shape and accurate dimensions.
Conventionally, this has been addressed by performing a process (closing process) in which a boundary line between plane element data elements is manually or automatically selected and closed by performing a merge process, or by performing a process which posits that all the generated plane element data elements are closed and automatically creates a closed solid model directly from all of the plane element data. Therefore, in some cases a shape of the generated three-dimensional model may differ greatly from the shape of the actual measured object, requiring significant amounts of time for subsequent correction work.
In order to resolve the above-noted situation, the present invention provides a three-dimensional model generating method, a three-dimensional model generating system, and a three-dimensional model generating program capable of readily generating a three-dimensional model having a desired shape and accurate dimensions based on measurement data.